how to convert bytea to String

[ketandba]

I am using postgres 8.0.
I have a table trn.
create table trn (trn_id int, trn_file bytea);

insert into trn(1,"myFile.doc");

myFile.doc is a wordfile.

I have successfully inserted data in trn table.
Now i want to retrieve trn table and change the contents of myFile.doc.
But by using this below code i can't retrieve myFile.doc in readble (String) form....
It give me the binary string....

How i get the content of myFile.doc in readable form...

	  public String   retrieveFile(int trnId) {
	        
	        
	        preparedStatement = null;
		connection 		  = null;
		InputStream is = null;
	      	StringBuffer out = null;
			
		try {
		 ApplicationDataSource ads = new ApplicationDataSource(Constants.DATA_SOURCE_NAME);
		connection = ads.getConnection();
		String selectSql = "select trn_file from trn where trn_id=" + trnId + ";";
						preparedStatement  = connection.prepareStatement(selectSql);
				
	ResultSet rs = preparedStatement.executeQuery();
							
	if(rs!=null) {
	    while(rs.next()) {
	        is = rs.getBinaryStream(1);
	        out = new StringBuffer();
		byte[] b = new byte[4096];
		for (int n; (n = is.read(b)) != -1;) {
						            out.append(new String(b, 0, n));
		}
		        
	        is.close();
	    }
	    rs.close();
	}
	preparedStatement.close();
			       
 } catch (SQLException sqle) {
	System.err.println("Retrieve content: " + sqle.getMessage());
 } catch (Exception ioe) {
	System.err.println("Writing stuff: " + ioe.getMessage());
 }finally {				
				closeDatasourceWrappers();
 }
  return out.toString();
 }

here is the snippet of my jsp page..

<% String selectedTrnId = (String)request.getParameter("trnId");
System.out.println("selectedTrnId in UpdateTranscriptedFile(jsp) ==> " + selectedTrnId);
TranscriptDAO trnDao = new TranscriptDAO();
String fileContent = trnDao.retrieveFile(Integer.parseInt(selectedTrnId));
System.out.println("******************************** ");
System.out.println("fileContent in UpdateTranscriptedFile(jsp) ==> " + fileContent);
%>
.....
.....
.....
<TR>
<TH align="right">File :</TH>
<TD align="left"><html:text property="trnFile" value="<%= fileContent %>" /></TD>
</TR>


So any how i want trn_file content in string form...and then update this content as and when require and again store in bytea format in database.

pl. help me out...
Thanks in advanced.
ketan

 

[sedj]

I take it by saying you have a "*.doc" file it is a MS Word document.
If this is the case, then of course you cannot convert it to a string - its just not possible - you need the MS Word or a programme such as OpenOffice to interpret the binary data into a readabke format.

If you want to edit the file, then you need to extract the binary data, and edit it in a programme that can handle that data - or write your own programme that can handle MS Word format (unadvisable and not easy).

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[stefanwagner]

There is a library to handle msword-documents, you might search for 'java poi'.

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